Research Of Detection Of Foodborne Pathogens In Chicken Based On Surface Enhance Raman Spectroscopy Technology

Foodborne pathogens,one of the public biological hazards,seriously threaten the development of the food industry and the health even the life security of consumers.Besides pork,chicken is considered as the second largest meat consuming product in China,which has high nutritional value,and a widely accepted by people in the world.But because of its high-water content,chicken is more susceptible to microbial infections.Therefore,the rapid detection of foodborne pathogens in chicken is very important to ensure its quality and maintain the health of consumers.Surface-enhanced Raman scattering?SERS?,a simple,fast and sensitive detection technology,has been widely used in material chemistry,food detection,environmental analysis,biomedicine and other fields.Therefore,the purpose of current work is by using SERS technology combined chemometrics to build a qualitative identification model and quantitative detection system with rapid and accurate detection of foodborne pathogens in chicken.The contents of this study are recounted as follows:1.The principle of SERS detection of foodborne pathogens.Here,the main influencing factors,material basis and classification trend of the SERS spectra of foodborne pathogens?four kinds of Pseudomonas were used as the object of research?enhanced by gold nanorods?Au NRs?were systematic studied.Firstly,a positively charged gold nanorods?Au NRs?SERS substrate was synthesized as a SERS substrate,which could enhance the Raman spectra of Pseudomonas through binding with the Pseudomonas by electrostatic adsorption.Next,the SERS spectra of four Pseudomonas species were collected.The main factors?included bacteria themselves,the adsorption degree and adsorption uniformity of bacteria and Au NRs nanocomposites?influencing the SERS spectra of bacteria were analyzed.The material basis?included proteins,amino acids,nucleic acids,lipids and other components on the surface of bacteria?causing the SERS spectra characteristic peakswere found.Finally,principal component analysis?PCA?and linear discriminant analysis?LDA?were used for the classification of SERS spectra of four kinds of Pseudomonas.While the main variables that caused the differences in the SERS spectra of Pseudomonas were screened out by using the LDA algorithm.It was found that the types and numbers of amide,C-C deformation and C-H stretch on the bacterial surface caused the classification trend.2.Qualitative detection of foodborne pathogens in chicken by label-free SERS technology.A recognition model that can qualitatively detect three Gram-positive pathogens?namely,S.aureus?ATCC 29213 and BNCC 186335?and L.monocytogenes?ATCC 19115??in chicken was established.First,a magnetic capture probe modified with vancomycin?Fe₃O₄@Au-Van?was synthesized,and the capture effects of Fe₃O₄@Au-Van for three pathogens were confirmed by plate counting method.Then,the SERS spectra of the above three pathogens at the concentrations of 10²-10⁴ CFU/mL were collected after captured by Fe₃O₄@Au-Van,and standard normal variate transformation?SNV?pretreatment was selected to eliminate the SERS spectral noise.Next,three qualitative identification models,namely soft independent modeling of class analogy?SIMCA?,K-nearest neighbor?KNN?and partial least squares discriminant analysis?PLSDA?were established,and the PLSDA model was optimized to identify the bacterial species in the real chicken samples as the PLSDA model had the highest recognition accuracy rate?training set was99.1%,prediction set was 90.3%?.Finally,the PLSDA model prediction results showed that the identification accuracy of S.aureus?BNCC 186335 and ATCC 29213?and L.monocytogenes?ATCC 19115?in chicken samples were 80%,90%and 90%respectively.3.Quantitative detection of the foodborne pathogen in chicken by SERS technology.A system for specifically and quantitatively detecting S.aureus?ATCC 29213?in chicken was constructed.First,Fe-MIL-88 nanometer enzyme and magnetic capture probe were synthesized by a one-step reaction method and characterized,respectively.Then the usage amounts of a magnetic probe for capturing S.aureus,of Fe-MIL-88 enzyme for catalyzing leuco malachite green?LMG,no SERS active?,of S.aureus aptamer for inhibiting Fe-MIL-88 enzyme activity were optimized to construct a reaction system which has the ability to connect S.aureus amount with the catalytic product?malachite green,with SERS active?amount.Next,the SERS signals of the system after reaction under different S.aureus concentrations were collected,and a standard curve was established between the SERS signals after SNV pretreatment and the logarithm of the concentration of S.aureus.The linear relationship was noted y=0.089x-0.155?R²=0.987?,and the limit of detection?LOD?was found 2 CFU/mL.Finally,the detection system and the plate counting method were applied to the detection of S.aureus in chicken samples,and the difference between the detection results of the two methods was analyzed by T-test,and the results showed no significace difference indicating the proposed method had excellent accuracy to quantify pathogen in real samples.This study aimed to provide a new methods and ideas for the rapid and accurate detection of foodborne pathogenic bacteria in chicken and other meat products.The findings of this reserch will help to reduce the detection time,operation produce and detection cost of foodborne pathogenic bacteria of food samples.The findings were also great signifcance for ensuring food safety,maintaining of consumer's health and promoting the development of the chicken industry.